But Apple and the FBI denied leaking the information. And now, a little-known publisher says his company was the source of the leak -- not the FBI or Apple -- and he apologizes.

Paul DeHart, chief executive of Blue Toad publishing company, told NBC News that after analyzing data released by the hackers and his firm's own servers, the two data sets are nearly identical, suggesting the leak came from his company.

DeHart said he does not know who stole the data from his company or whether it had been shared with anyone else. He said the data had been stolen "in the past two weeks."

"We're pretty apologetic to the people who relied on us to keep this information secure," he told NBC News.